


Forever (Means Nothing Without You)

by LunarHermit



Series: Everything Stays (Everything Changes) [4]
Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Angst, Blood Drinking, F/F, Female My Unit | Byleth, Fluff, Hurt/Comfort, Please read warnings at beginning of chapter, Silver Snow Route, Spoilers, headcanons
Language: English
Status: Completed
Published: 2020-04-13
Updated: 2020-04-13
Packaged: 2021-03-01 20:01:13
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 8,172
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23632768
Author URL: https://archiveofourown.org/users/LunarHermit/pseuds/LunarHermit
Summary: Byleth’s gaze rose to the green-filled sky, the great white figure up above leaking more corrupted magic with each roar of maddened fury.Her tears finally spilled down her cheeks – slowly, at first, and then in thick rivulets - and as they did, Byleth could not help but think that it was fitting.For the second time in her life, Byleth cried tears of loss for one she had come to love.
Relationships: My Unit | Byleth/Rhea
Series: Everything Stays (Everything Changes) [4]
Series URL: https://archiveofourown.org/series/1563757
Comments: 8
Kudos: 52





	1. Part One - Wail

**Author's Note:**

> This was originally a oneshot (that I had promised forever ago) but due to what might be a trigger warning for some (specifically the opening of a vein) halfway through, I decided to split it up. I don't know if this really _needed_ a warning, but I thought I'd better be safe.
> 
> Part 1 = angsty
> 
> Part 2 = headcanons & trigger warning
> 
> Part 3 = hopeful fluff (Part 2 is referenced)
> 
> This way, if you really have to, you can just skip Part 2 and jump straight to Part 3 without missing too much.
> 
> This is my take on the Rampage and Wailing scenes at the end of the Silver Snow route, as well as the aftermath.

**-++-**

Despite the small thoughtful frown that adorned her face at the secrets being revealed - the only indication of the turbulent thoughts swirling within - Byleth continued to gaze at the visibly weak woman in front of her with thinly veiled concern. While the current conversation was obviously important to Rhea, and Byleth _was_ happy to finally have some answers to the many questions she had about her past, she truly believed that it could have waited until the other woman didn’t look as if a gentle wind might topple her. Not only had Rhea just awoken after overexerting herself barely a week before in Shambhala, but Byleth could tell that the emotionally charged conversation was taking a visible toll.

It took a great deal of effort for Byleth to stand there in the early morning gloom and listen calmly to Rhea’s broken and emotional words, when all she wanted to do was bundle the pale woman up and usher her back to bed. 

It was this careful scrutiny of the other woman that allowed Byleth to catch the faint gasp that escaped her lips as she suddenly stumbled midsentence. Alarmed at this turn of events, Byleth took an unconscious step forward just in time to witness Rhea’s pale green eyes widening in surprised pain before the pupils contracted until they were no more than vertical slits. 

“What… No…” Rhea whispered, her hands raising to press against her chest. She could feel her Crest Stone - her _heart_ \- beating painfully, a violent sure of magic flooding through her veins with each pulse. “No…” 

Rhea staggered once more as the pain grew sharper, uncontrollable. A pained cry tore itself from her throat. “ _Arrgh!_ ”

Seteth, having been focused on Byleth’s reaction, was only just realizing something was wrong when Rhea screamed. He whirled around to face the woman he _knew_ was still incredibly weak in panicked concern. 

“Rhea?!” Seteth took a step forward only for her to bend in on herself in pain. “Rhea!”

“What is wrong?!” Flayn’s worried voice spoke up from the other side of the woman in question. Her hands fluttered hesitantly in front of her, uncertain as to how she could help. “Please calm yourself, Rhea!”

Rhea screamed once more, her voice deepening halfway through as she began radiating untamed power. 

Byleth could only watch, frozen, as the glowing motes of magic visibly wafted off of Rhea’s bent form in waves. Her normally soothing magic felt twisted and corrosive as it lashed forcefully through the air, causing Seteth and Flayn to stumble backwards, before utterly consuming her in its green light.

“Is the power of the Crest taking over her body?” Seteth shook his head side to side in alarm. “Why is this happening?!”

The words had barely left his lips when the power flowing from Rhea suddenly erupted violently. Three sets of green eyes immediately jerked skywards, speechless, only to watch as a great white figure burst forth from the green light with an enraged roar that shook the very air around them.

A Knight of Seiros swiftly approached, unseen, as the three continued to stare up at the transformed archbishop in numb horror.

“Seteth! It’s terrible!” The Knight puffed, out of breath. “White Beasts have appeared all over Garreg Mach!” He shook his head as Seteth turned to look at him sharply. “It’s hard to believe, but there have been reports that the priests and knights have been changing form.”

“White Beasts…” Seteth trailed off in disbelief, before a disturbing thought occurred to him. “Are they the ones Rhea shared her blood and stones with?”

Before Seteth could contemplate the matter further, a church soldier came running from the opposite direction, his voice in a panic.

“Seteth!” The soldier shouted as he neared. “Demonic Beasts are heading this way!”

“With the amount of power she is radiating like a beacon… They are after Rhea.” Seteth concluded abruptly in sudden understanding. He then shook his head, voice grave. “Professor, our situation is dire.”

Seteth gnashed his teeth and growled lowly in helpless frustration before turning a heavy gaze upon Byleth. His voice was thick with dismay. “If we do nothing, Fódlan will be destroyed by a rampaging Immaculate One and these - these _children_ of hers.”

Byleth gazed back at the visibly distraught man in blank incomprehension.

Seteth’s voice wavered. “There is only one way to stop this. We… we _must_ …”

Byleth’s eyes slowly widened as it dawned on her just what the man was saying. She shook her head silently. No. He couldn’t _possibly_ be asking her to- Not when he _knew_ -

“Damn it.” Seteth closed his eyes, unable to look at the disbelieving ones staring back at him in mounting horror. He clenched his teeth harder and snarled, utterly disgusted with himself in that moment. “ _Damn it!_ We have no choice!”

“Brother?” Flayn’s voice broke as she looked at her father with worried eyes.

Byleth simply shook her head silently, jerkily, her throat refusing to form the words she wanted to scream.

“We have no choice but to kill the Immaculate One… to kill _Rhea!_ ” Seteth finally bit out.

“No…” A pained gasp broke forth from Flayn at his words, her hands rising to cover her mouth in horror as her eyes widened in disbelief. “Brother, _no_ …”

As if the word had suddenly been unlocked in her mind, Byleth began silently repeating the word ‘no’ over and over as she stared at the ground in blank denial.

“Professor,” Seteth spoke as he stepped closer to the young woman, though the only response he received was for her to step back and shake her head harder. Moving closer still, he clasped her shoulders in his hands tightly. He could feel her small frame tremble within his grasp. “ _Byleth_.”

Byleth finally looked up, unshed tears glistening in her green eyes as they locked with Seteth’s sorrowful ones. 

“Please don’t-,” She rasped quietly. “I _can’t_ -,”

“Byleth,” Seteth’s voice gentled. He knew what he was asking her, but they had no choice. “Byleth, _Rhea_ asked you to protect this world – to _save_ Fódlan.” He shook his head apologetically, despair equally visible on his own face. “She does not want this.”

Byleth’s breath hitched, and she shook her head again, desperately. “ _Please_.”

“ _She does not want this_ ,” He emphasized, voice raw. He could feel the trembling grow in strength at his words, and his eyes closed briefly in shared pain.

Byleth felt so many things in that moment – pain, despair, anger - and yet at the same time she felt a sense of disconnect, a numbness that she hadn’t experienced in over five years. Her memories helpfully supplied her with the image of a muddy field, her hands clutched into the front of her lifeless father’s armor as the rain obscured her tears.

Her heart did not beat. It had _never_ beat.

So why, then, did it _hurt_ so much?

Byleth’s gaze rose to the green-filled sky, the great white figure up above leaking more corrupted magic with each roar of maddened fury.

Her tears finally spilled down her cheeks – slowly, at first, and then in thick rivulets - and as they did, Byleth could not help but think that it was fitting.

For the second time in her life, Byleth cried tears of loss for one she had come to love.

**-++-**

Garreg Mach, still bearing the scars of the Five-Year War, had once again become a battlefield.

With the sheer amount of White and Demonic Beasts in play, it had become necessary to split their forces accordingly. Byleth’s students, as well as the majority of the knights and soldiers left unchanged by Rhea’s corrupting power, were scattered throughout Garreg Mach in an attempt to both hold off the Beasts and evacuate what civilians were still within the grounds.

Byleth, Seteth, and Flayn - the three closest to Rhea – as well as a handful of Knights, were left to deal with the Immaculate One herself.

The fight was not going well.

Though the Knights were strong and well trained, it quickly became clear that their weapons of silver and steel were insufficient to act as anything more than an annoyance to the mad dragon. Swords, axes, lances, arrows – all bounced harmlessly off of gleaming white scales. Not even the few mages present could muster up enough power to make the Immaculate One do more than growl in irritation, their spells splashing harmlessly against her thick hide.

The battle seemed hopeless, until all of a sudden, the great white dragon let out a roar of surprised pain.

Byleth almost dropped her sword in horror as she stood frozen, her eyes fixed on the small trail of green blood oozing from a would just below Rhea’s right wing. 

A wound she had caused.

A pit opened within her, and Byleth staggered, suddenly nauseous.

Seteth, having noticed what happened, yelled down from his perch atop his wyvern. “Byleth, _move!_ ”

Byleth jerkily stumbled back just in time to avoid a set of large teeth snapping closed around the space she once occupied. The white head started towards her new position mere moments afterwards, only to jerk upwards with a deep roar before the red eyes shifted focus. Byleth numbly took in the sight of Seteth swooping just out of reach of glistening white fangs, his silver axe having been exchanged for the Spear of Assal now clutched tightly in his hand.

Byleth’s grip around her sword trembled as she came to the same conclusion Seteth had moments before.

Rhea’s scales were too hard and magically resistant for mortal weapons to pierce.

Relic weapons, it seemed, were the exception - considered divine by most, the awesome weapons gave their bearers access to power beyond mortal ken. Therefore, while the Knights could act as a distraction at best, only Seteth and Byleth could actually _harm_ the rampaging dragon.

Bile rose in Byleth’s throat, and it took all she had at the moment not to bend over and empty what little was left in her stomach as the reality of what must happen echoed throughout her mind.

Only Seteth and Byleth wielded weapons capable of dealing the killing blow.

Except Byleth wasn’t certain if _she_ was capable.

Perhaps she could have, once, when she was a simple mercenary with muted emotions. The Ashen Demon would have been able to do what was required, no matter how personally involved she was in the matter. _She_ was cold and calculating, a terror on the battlefield who took no quarter and always completed the job.

Byleth had not been the Ashen Demon for quite some time.

 _Now_ Byleth had full access to her emotions. She _felt_ , and she felt _strongly_. The very thought of completing _this_ job had her trembling like a leaf, a cold sweat breaking out across her brow as her stomach tied itself into knots.

Byleth looked at the great white dragon before her, and all she could see was a pair of gentle green eyes smiling at her warmly. 

She listened to the dragon roar in pain as Seteth struck blow after blow, and all she could hear was the broken gasp of anguish and hope as Rhea fell into her arms deep below the Imperial Palace. 

She was aware that the violent magic radiating off of the enraged dragon was choking the air, yet all she could feel was the soothing sensation of warmth suffusing her as she drifted between consciousness and unconsciousness, a soft voice humming a gentle melody as her aches and pains eased until they were no more.

The battle raged onwards, and yet with each blow Byleth numbly struck, her own strength dwindled until it was all she could do to just remain standing.

It took what felt like hours, but eventually the great dragon’s attacks lessened in intensity, her thrashing becoming weaker even as her roars increased. The Immaculate One’s tough hide, once thought impenetrable, was covered in gashes and gouges of varying lengths, her once gleaming white scales almost completely obscured by thick green blood.

Byleth’s fingers spasmed around the hilt of her sword, its bony teeth a glistening green.

In that moment she knew, with a sense of sudden clarity, that she could not do it – not when she looked at the Immaculate One, and all she saw was Rhea.

As if realizing that Byleth’s thinly held together resolve had finally shattered, Seteth firmed his grasp on his spear. Lifting it into position, he directed his wyvern to dive, intent on finally putting an end to the tragedy before him.

Perhaps it was instinct, or perhaps simple luck, but just as Seteth entered striking range the Immaculate One turned, her tail lashing out and managing to knock his wyvern out of its dive and send it careening into a broken pillar.

“ _Father!_ ” Flayn cried out in shocked concern, her attention immediately diverting to the downed wyvern and its rider.

Noticing the great white head moving towards the distracted girl, Byleth’s grip on her sword instinctively tightened and she darted forward, arriving just in time to block rows of sharp teeth with her Relic. Gritting her teeth, Byleth used the last of her strength to push aside the weakened head, reflexively following up with a thrust towards the unprotected chest before her. It was only as the sword in her hand glowed red and lengthened into a bony whip did Byleth’s eyes widen in realisation, but by then it was too late.

The sharp end of her lengthened sword easily pierced the vulnerable scales and sunk deeply into the Immaculate One’s chest, the great dragon thrashing immediately and letting out the loudest roar of agony yet. Numbly, Byleth retracted the sword, the sickening suction sound it made as it pulled free from Rhea’s chest echoing in her ears.

The Immaculate One launched into the air as soon she was free, though the countless wounds she had endured caused her once graceful flight to suffer greatly, her injured form wobbling and listing as she struggled to keep airborne.

Byleth did not hear nor see the others around her, though it vaguely registered that some called her name in both concern and relief. She only had eyes for the wounded dragon struggling in the sky, and without even considering her actions she began to give chase. Running unseeingly across the battlefield, Byleth kept her focus on the figure up above as the sun’s rays finally broke through the heavy clouds, the bright light illuminating the glistening figure in its glow. 

Byleth sped across the bridge as the dragon listed in between the cathedral’s towers and briefly out of sight. She made it into the grand building just as Rhea crashed before the altar in a cloud of dust, a great roar of pain leaving her blood-stained maw as she arched, the impact having jostled her many injuries. Byleth jerked to a halt just out of reach of the large white wings moments before Rhea collapsed to the ground completely.

Sunlight spilling in from a hole in the ceiling up above cut through the gloom suffusing the battered cathedral, and through the dust settling around them Byleth could see Rhea’s large form shudder in pain, her breath coming in wheezing gasps. Byleth stood frozen, green eyes staring blankly at the downed dragon and yet lost as she was in her own mind she was not truly _seeing_. Her emotions roiled within her, a violent mix that left her gasping for breath as well. 

Was this to be the end, then? After all she’d fought for, all she’d accomplished, all she’d _lost_ – was _this_ to be her reward? To have to watch another she loved die in agony, and this time by her own hand?

She had never before longed to turn back time as much as she did in that very moment.

She knew if she did, however, that she would not be able to muster up the strength to strike Rhea down a second time - and the world would suffer for it.

Byleth wished desperately that Sothis were still present, that the goddess - the constant companion she’d come to rely on for support - would know what to do, know how to fix this nightmare she could not awaken from.

Because for all the power that she had been gifted, Byleth had never felt more helpless - more _hopeless_. 

Fate, Sothis had called it, when even the manipulation of time could not save a life.

Byleth would give all of her not inconsiderable power if only she could defy fate _just this once_.

Lost as she was within herself, Byleth at first did not notice as the light illuminating the great dragon’s form began to brighten - it was only as she began to feel the warmth emanating from in front of her did she finally snap out of it.

Her green eyes slowly widened as she watched Rhea’s wounded form become bathed in a golden glow, her pained sounds lessening as the light slowly brightened. A tinkling voice, soft as a breeze, whispered across her mind. It was achingly familiar, and though she could not understand the words being spoken, Byleth almost instinctively understood the emotion behind them.

Familiar white flower petals slowly began wafting off of the dragon’s now docile form as Byleth watched, mesmerized.

Lilies.

They were white lilies.

Just like _she_ wore in her hair.

The delicate petals danced and swayed as they slowly floated upwards in an unseen breeze, the glow brightening until it nearly obscured the Immaculate One from view. The slackened grip Byleth had on her sword finally yielded, and it was with a sense of relief that she let the Relic fall limply to the marble tile beneath her with a clatter. 

She would not need it.

The light grew blinding, yet Byleth did not dare avert her eyes. She did not blink. Frozen, she stared into the golden light and let the waves of warmth wash over her.

In that moment, she heard a familiar voice - though she did not hear it with her ears.

_“What a troublesome child you are - don’t tell me you’ve gone lazy without my guidance. I refuse to do everything for you, you know…”_

The blinding light slowly faded enough for her to see again, and Byleth was shocked to realize that the dragon no longer lay collapsed before her. Gaze darting around almost frantically, she finally looked up, a small gasp escaping her as her eyes widened. 

Byleth stood, awestruck, as floating slowly downwards in the golden light was not the Immaculate One’s limp form, but _Rhea’s_. Long green hair fluttered calmly in an unseen breeze, the simple white robe she wore before losing control now splattered with crimson. Impossibly, the unconscious woman also wore her cloak and headdress when before there was none.

It was Rhea as she’d come to expect her – resplendent in her archbishop regalia and flush with life. Not the pale and sickly woman she’d been constantly worried about since rescuing in Enbarr.

_“Well, go on then. It is terribly rude of you to make my daughter wait.”_

Snapping out of her awe, Byleth darted forward before coming to a stop beneath the falling woman, arms held out in front of her. Moments later soft cloth brushed against her palms before a slight weight settled within her arms. Clutching her precious cargo to her chest, Byleth silently stared down at Rhea in a mixture of concern and awed relief.

Rhea stirred slightly, her head turning as a light sigh escaped her parted lips. Slowly, hazy green eyes opened. Rhea blinked almost weakly in the shining light, her eyes remaining somewhat unfocused as she stared upwards. 

A small gasp escaped her, and her eyes widened before softening to reflect the small tremulous smile curling her lips. “You’re here, Mother…”

In that moment Byleth knew that it wasn’t her that Rhea was seeing, and she couldn’t help but think back to the softly teasing words she’d heard when she’d thought all hope lost. Silent gratitude echoing throughout her entire being, Byleth hugged the woman in her arms more securely against her chest.

Comforted, Rhea’s eyes slipped closed once more, her head turning to nuzzle into the warm embrace.

**-++-**


	2. Part Two - Blood

**Notes for the Chapter:**

> (possible) Trigger Warning for opening a vein (for blood sharing purposes)
> 
> And also headcanons.

**-++-**

Seteth rushed into the cathedral behind Flayn, the tall man sporting an obvious limp.

“Byleth!” Seteth called out. He noted with a sense of worry that the woman in question stood motionlessly at the other end of the grand chamber, her back towards them and posture bent forward slightly. “Are you injured?”

“Is that…?” Flayn’s eyes narrowed as she noticed what her father did not, and she put on a burst of speed. 

Byleth turned around at their words, and Flayn’s eyes widened in shock as she realized just who was cradled protectively to her chest.

“Rhea?!” Flayn gasped, a hand flying to her mouth.

“What? Impossible!” Seteth breathed as he caught up to his daughter, the two of them staring down at the unconscious woman in surprise. “One does not simply _recover_ from their Crest-,” He shook his head in incredulity. “How is this possible?”

Byleth’s eyes reluctantly raised from concentrating on the slight rise and fall of Rhea’s chest, irrationally afraid that if she looked away the limp woman would stop breathing. She locked eyes with Seteth, his gaze both confused and relieved in equal measure.

“Sothis,” Byleth stated simply. That was really all she needed to say – divine intervention was the only reason Rhea yet lived.

“I see blood.” Flayn shook off her shock first, a frown settling on her exhausted face. “Is she still injured?”

“I- I don’t know,” Byleth shook her head, eyes flicking from Flayn back down to make sure Rhea was still breathing. She hadn’t yet had time to check. “She woke up and spoke briefly, before falling unconscious once more.”

“That is a good sign, at least,” Flayn assured in relief, before affecting the same serious tone all healers seemed to excel at. She motioned to the tiled floor between them. “Please place her down on the ground so that I may examine her.”

Byleth’s arms reflexively pulled Rhea closer, her eyes flicking uncertainly between Flayn’s expectant gaze, the floor below, and the woman in her arms.

“Professor – _Byleth_ ,” Flayn’s voice gentled as she explained her request. “Perhaps you do not realize it, but your magic is currently encompassing the both of you.”

Byleth blinked, startled, before looking down at Rhea more closely. She had been so focused on making certain that the other woman was breathing, that she hadn’t noticed the faint golden shimmer encapsulating the both of them wasn’t simply due to the sun’s glow.

“While I am certain that your magic could only be helping Rhea,” Flayn continued. “I will be unable to get an accurate read on her current state with its interference.”

Byleth bit her lip before nodding in acquiescence. Slowly, hesitantly, she lowered the unconscious archbishop and gently laid her upon the ground. As soon as her hands were free, she shucked off her white and purple cape and bunched it up before placing it beneath Rhea’s head. That done, she took two tiny steps backwards and hovered anxiously as Flayn began her examination.

Flayn kneeled down next to the prone woman and waited as the gentle golden glow of Byleth’s magic faded completely, before placing her hands over Rhea’s chest. Calling forth her own power, a green light began emanating from her hands as she focused. Her expression of deep concentration almost immediately twitched into a small frown, a fact that did not go unnoticed by her onlookers.

“Is she well?” Seteth asked worriedly.

Byleth’s fingers twitched forward before she pulled them back, clenching her hands into fists so as to curb the temptation to reach for Rhea once more. 

Flayn did not speak for a long while, focused as she was on directing her green magic to heal. Finally, she sighed, her magic dimming yet not fading away completely. She looked up at the worried faces on either side of her. “What wounds were left after the miracle that saved her life were mostly superficial, and I have done what I can for them…”

“But?” Byleth blurted nervously, shifting anxiously on her feet.

“…She is very weak,” Flayn finally admitted. As Byleth stiffened, Flayn shook her head quickly. “I am not saying that she is at death’s door, however she is both physically and magically drained. You said that she regained consciousness long enough to speak?” 

Flayn waited for Byleth to nod in confirmation before pursing her lips in thought. Slowly, she nodded as well, a theory unfurling in her mind. 

“I believe that was due to your magic bolstering her, as her Crest Stone is only just producing enough magic to sustain her life.” Flayn explained slowly, before sighing with a small frown. “If it continues at this rate, I do not envision her awakening again for… quite some time.”

Seteth rubbed his face in weary relief. “So she is entering a healing sleep? That is… good, I suppose. Better than the alternative, at least.” 

Byleth stared down at the still woman, conflicted. She bit her lip before speaking into the ensuing silence, her voice soft and incredibly small. “…How long?”

Flayn and Seteth shared a look. 

“My injury was not the same, though I also required a great amount of time to heal,” Flayn said after a long moment. Her voice wavered as she thought of all she had missed during those long years of sleep. “I slept for years. _Centuries_. It is… one of the reasons why I do not care for sleeping now.”

Seteth closed his eyes in remembered pain at the long years of anxiously awaiting his daughter’s return to consciousness, of praying year after year that he might soon get to glimpse her sparkling eyes and joyous smile once more.

“Is there nothing we can do?” Byleth asked, voice trembling slightly.

“I am sorry, Byleth,” Seteth shook his head and sighed wearily in resignation. “If it is as Flayn says-,”

“Perhaps there is,” Flayn piped up suddenly, a thoughtful look on her face. She immediately gained both her father’s and Byleth’s full attention. “Perhaps there _is_ a way to hasten her recovery.”

“Whatever do you mean, Flayn?” Seteth questioned with raised brows.

“Blood.” Flayn said simply.

“What?” Seteth asked, startled. “Flayn, you know that if she is as weak as you say, introducing the power of another Crest might-,”

“Not just _any_ Crest,” Flayn shook her head stubbornly at her father’s words, though her gaze never left Byleth’s. “The Crest of Flames is _different_ , is it not? The power of the progenitor god is different than ours – _greater_. And that power now flows through Byleth’s blood.”

“I-,” Seteth blinked in surprise. His hand rose to rub at his chin before settling across his mouth, expression turning thoughtful. “Hmm…”

Byleth looked between father and daughter, expression unsure. “It won’t harm her?”

“Normally I would advise against it. As I had begun to say, introducing the power of a different Crest into her system while her Crest Stone is barely able to produce enough magic to sustain her would likely be a disaster. The foreign Crest would most certainly overwhelm her without the buffer of her own magic.” Seteth explained slowly. “Flayn is correct, however – the power of the Crest of Flames is… how do I put this…”

Seteth frowned for a moment as he mulled over how best to explain. “All Crests stem from one source – the progenitor god. Therefore, the Crest of Flames - _your_ Crest - would not be seen as foreign. Instead of _vying_ with Rhea’s Crest, it would in theory be welcomed and _bolster_ it.”

“I would not recommend attempting a transfusion if you simply carried the Crest, however.” Seteth warned suddenly. “But since it is true that you _also_ carry the Crest Stone and have been blessed with the progenitor god’s power… Well, it might just work as Flayn believes.” 

“And it _won’t harm her_?” Byleth insistently repeated, gaze jumping from Seteth to Flayn expectantly.

“No,” Seteth shook his head at last. “No, I do not believe that it will. It might not work as intended, but it in that case the effects would be benign – it would not harm her.”

Byleth nodded, then asked suddenly, “What must I do?”

“Are you certain?” Seteth asked in concern. “You do not have to-,”

“Seteth,” Byleth cut the older man off. Her expression was serious, determined. “What must I do?”

_She_ was the one who struck the final blow. _She_ had caused Rhea’s weakened state – and now _she_ was going to _fix it_.

“…Very well,” Seteth nodded slowly, convinced that nothing he could say might sway her. “For this to work on a human, the Crest-bearing blood would need to be transfused directly into their bloodstream.”

Byleth nodded, knowing that was what occurred to save her father’s life.

“Our physiology is different – Crests are not a foreign entity, but a very integral part of what we are. Because of our Crest Stones, we are able to absorb the power without it being so directly transfused.” Seteth explained. At Byleth’s look of confusion, he simplified, “Having her consume the blood would be more than sufficient – her Crest Stone will absorb the power contained within and do the rest.”

Expression clearing, Byleth nodded in understanding. Moving closer, she kneeled next to Rhea’s head before reaching for the dagger at her waist. Unsheathing the sharp blade, she brought it up to her wrist only to hesitate as the cold steal touched her skin.

“I know you said it wouldn’t harm her, but,” Byleth asked in concern. “Will this work even if I’m not a Nabatean?”

“But do you not see, Professor?” Flayn looked into startled green eyes with a small yet genuine smile. “You _are_ one of us.”

Byleth’s gaze jumped to Seteth in muted disbelief at Flayn’s words, but contrary to her expectations the tall man just smiled faintly and nodded in agreement.

“Oh,” Byleth blinked, then put that piece of information aside to think upon at a later date.

Concerns assuaged, she drew a small line across her skin, red blood instantly beginning to well up. It took only a few seconds for a few drops to roll down her palm and drip off her fingers before splattering against the floor below. Seteth immediately kneeled and gently pried Rhea’s mouth open before moving his hand to rest gently against her throat to make certain that she swallowed. Byleth pressed her weeping wound against Rhea’s parted lips, taking care to position herself so as not to allow any more of her blood to spill onto the floor.

They stayed like that for long minutes, Seteth occasionally massaging Rhea’s throat to aid the unconscious woman in swallowing while Flayn kept careful watch with her magic, before there was any sign of change.

Byleth twitched slightly as she felt a faint suction against her wound. The sensation - while not entirely pleasant - was not exactly what she would consider painful, and simply came as a surprise.

“I am beginning to get interference from the Professor’s magic,” Flayn noted with a frown of concentration. Her eyes immediately rose to meet Byleth’s, a reassuring smile settling across her face. “That is a good thing, as it means your magic is successfully being spread throughout her system. And though I can no longer examine her quite so thoroughly, I _was_ able to determine that the magic being produced by her Crest Stone had risen slightly.”

Byleth nodded, eyes shining in relief. She unconsciously pressed her skin slightly harder against Rhea’s lips, though almost jumped in shock when a soft tongue brushed against her in response. Seteth’s words distracted her from the odd sensation, and she turned her head to look at him.

“She seems to be swallowing on her own now,” Seteth observed, though he kept a supervising eye on the faintly moving throat. He only briefly glanced up at Byleth to warn, “You must stop as soon as you start to feel weak. There is no point in hastening Rhea’s recovery only for you to collapse as well.”

Byleth nodded outwardly, though she was silently determined to give Rhea as much of her blood as the other woman needed.

She did not mention when the faint suction grew in strength, nor did she mention the slight buzzing she began to feel in her head soon after.

_”Byleth!”_

__A voice cried out, piercing the fog that had creeped upon her thoughts after long seconds – minutes? – of sharing her blood._ _

__Byleth blinked slowly, sluggishly. She shivered, suddenly very cold, and thus the slight fizzling warmth she felt flow throughout her wrist was entirely welcome – if rather confusing. Following the length of her arm with her eyes until she reached the end, she looked dazedly in confusion at the large hand holding her by the forearm, and the smaller one hovering over her red wrist with a green glow._ _

__She suddenly frowned and tried to pull her arm away – she was supposed to be giving Rhea her blood, not letting it spill to the floor. Her weak tugs were unsuccessful, the grip holding her arm in place tightening in response to her efforts._ _

__“Byleth, stop moving so that Flayn can finish healing you,” Seteth barked, causing a set of dazed green eyes to connect with his own in confusion. He sighed and shook his head, irritably muttering to himself under his breath, “I should have known better than to trust you to stop when you reached your limit.”_ _

__“Rhea-,” Byleth croaked, her mouth oddly dry._ _

__“Is currently in a much better state than yourself,” Seteth cut her off with a scowl. “Not surprising, seeing as she now currently possesses nearly half of your own blood within her.”_ _

__Byleth opened her mouth once more to argue only for a bright green glow to eclipse her vision. Her heavy eyes slowly slipped closed and she only faintly registered the feeling of arms catching her as she began to fall.__

__**-++-** _ _

_  
_


	3. Part Three - Warm

**Notes for the Chapter:**

> A bit of fluff to soothe the ache.

**-++-**

Light spilled in though a break in the curtains, illuminating Byleth’s sleeping face in its bright glow. Disturbed, her brows furrowed slightly, and she eventually began to stir. Green eyes slowly fluttered open, her vision hazy as she found herself gazing up at a ceiling. She could feel that she was laying on her back on something soft – a bed – though she could not recall having gone to sleep. Blinking slowly, her vision eventually came into focus, and she swept her eyes around her unfamiliar surroundings in confusion.

Her searching gaze eventually caught on the only familiar thing in sight - a green-haired man sat slouched in a chair on the other side of the room.

“Seteth?” Byleth rasped in confusion, her voice dry and cracked.

Seteth straightened abruptly at her quiet words, his eyes immediately swivelling to meet her own. He stood up - his chair screeching slightly against the floor in his haste - and walked swiftly to her bedside.

“How do you feel?” He asked with a light frown, worried gaze scanning her expression for any potential falsehoods.

“Sore. Tired.” Byleth admitted after a moment of reflection. “Confused.”

Seteth nodded with a relieved sigh, his posture relaxing somewhat at her response. “That is to be expected.”

“What-,” Byleth swallowed, yet her throat remained dry. “What happened?”

“What happened?” Seteth’s expression darkened, a scowl sliding onto his face as he fixed her with a disapproving gaze. His voice took on a lecturing tone. “What happened is that, _despite_ my warning, you continued to give Rhea your blood well passed the point of personal safety. I had to pull you away so that Flayn could shift her healing to _you_ instead of Rhea. What you did was quite foolish, and if it were not for-,”

Byleth’s brows furrowed as she struggled to remember the events he was describing. Memory suddenly returning in a flash, Byleth’s eyes widened. She blurted, “How is Rhea?”

“You did not hear a thing I just said, did you,” Seteth grumbled as he rubbed his forehead in exasperation. He finally sighed, “Rhea is currently in her room resting after her trying ordeal, as should you be.”

“Did it work?” Byleth asked, gaze intense.

“While she is still weak and has yet to awaken,” Seteth started, only to continue with a slightly faster pace as Byleth’s eyes widened in alarm. “Flayn assures me that she is now producing a sufficient amount of magic, and so should not be too long in awakening.”

Byleth’s only response was to weakly push the blankets off of her. Struggling to sit up before Seteth could stop her, she swayed, suddenly lightheaded.

“What do you think you are-,” Seteth reached for her shoulder and tried to gently press her back into the bed only for her to resist. He groaned in exasperation. “I said that you should be _resting_. What you are attempting to do is the complete opposite of resting, as I am sure you are well aware.”

“I need to see her,” Byleth stated, attempting to shrug off Seteth’s hand.

Seteth closed his eyes briefly, a frustratedly resigned expression settling across his face. “Am I to understand that you will continue your ill-advised attempts until you end up collapsing?”

Flashes of the fight with the Immaculate One flickered across Byleth’s mind, as well as its aftermath, firming her resolve. She stared up at Seteth in silent challenge, a stubborn set to her jaw.

“Very well then.” Seteth acquiesced irritably, before warning, “But you will only do so with my aid.”

Byleth nodded in acceptance, and only then did his hand and arm move to slide under her own and across her back. It was perhaps just as well that he offered his aid – Byleth was surprised to note just how unsteady she was on her feet, and the short walk down the hall to Rhea’s room left her exhausted to the point that Seteth ended up carrying most of her weight.

As soon as they entered the silent room, Byleth only had eyes for the figure sleeping peacefully in the center of the large white bed, the canopy drapes half-closed so as to stop the light spilling in through the large windows from disturbing her. Standing at her bedside, Byleth’s gaze flittered about. She carefully took in the measured rise and fall of Rhea’s chest, the lustre to her once brittle hair, and the absence of unnatural pallor in lightly pinkened cheeks. 

Some unnameable tightness within her chest unclenched, and Byleth all but sagged against the side of the mattress.

“We should get you back to bed,” Seteth said eventually, only for Byleth to shake her head.

“I… I would like to stay,” Byleth murmured softly, eyes never leaving Rhea.

Having expected such a response, Seteth nodded. “Very well, but you must _rest_.” 

Allowing her to rest most of her weight against the bed, Seteth reached out and pulled down the covers before helping Byleth climb in. He waited until she had situated herself before pulling the blankets back up and tucking them once more around the bed’s occupants. He warned softly, “I am quite serious, Byleth. You must rest.”

Byleth nodded in understanding, her eyes already starting to droop. Not waiting for the soft footfalls to fade away entirely, Byleth shifted until she was brushing against Rhea’s side, the other’s warmth seeping into her pleasantly. One hand crept up only to splay softly atop a gently rising chest, the faint yet steady beating doing more to sooth her concerns than anything else. Sighing in content, Byleth’s eyes slipped closed.

**-++-**

The second time Byleth awoke, she was more comfortable - and more confused - than the first.

The first thing she noticed was that the persistent chill she’d been plagued with was finally gone, and in it’s place she felt a pleasant warmth. The second thing she noticed, was that she could not just hear but _feel_ a steady beat, as if a soothing drum were being played close enough to feel the vibrations. The third, and most confusing, was that she was laying atop something very soft.

And that something was moving, albeit gently.

Blinking her eyes open, a small yawn escaped Byleth as she raised her head slightly to alleviate her curiosity. It seemed that, despite having fallen asleep next to Rhea, sometime during her rest Byleth had shifted closer until she was literally laying atop the other woman. Her body was snugly pressed along the length of Rhea’s, their legs entwined, while her head had been pillowed upon Rhea’s chest.

The drum she had heard was Rhea’s heartbeat, soothing and strong.

Byleth frowned sleepily in thought, eyes briefly catching on the slight smile curling lightly parted lips, before finally coming to a decision. She gently laid her head back down once more before snuggling into the warmth. She couldn’t be bothered to move - not when she was not only extremely comfortable, but exactly where she wanted to be.

The arm wrapped snugly around her waist suggested that the slumbering woman below her felt the same.

She had just closed her eyes and was about to let herself drift off once more when a familiar voice called to her softly from across the room.

“Professor?”

Byleth’s eyes opened, her gaze sliding across the bed and coming to a rest on the young woman now standing at the bedside.

“How are you feeling?” Flayn asked, gentle voice carefully lowered so as not to disturb Rhea’s rest.

Byleth blinked gradually, before murmuring, “…Warm.”

Flayn smiled at that response. She took in their positions that still remained unchanged from when she had entered the room hours ago, and also recalled the golden glow of Byleth’s magic stubbornly clinging to Rhea as she held the weak woman protectively in her arms. 

“You love her,” Flayn stated simply, softly.

Byleth was silent for a long while, gaze turning thoughtful as she listened to the soothing beat beneath her ear. Finally, she nodded slightly, solemnly. “I do.”

Flayn’s answering smile was as blinding as it was sweet.

“How is she?” Byleth murmured after a moment of silence, brow pinching slightly in concern.

“Rhea is doing quite well,” Flayn explained, her observant gaze watching as the expression of concern on Byleth’s face smoothed out in relief. “The transfusion was a success. The power of your Crest was able to strengthen Rhea’s weakened Crest Stone just enough for it to once more begin producing the necessary levels of magic for her to heal.” 

“Good,” Byleth yawned.

“But after your actions in the cathedral, you were slightly worse off,” Flayn’s smile turned into a stern frown. “Which is why I shall once more leave you to your rest.”

“Okay,” Byleth nodded acceptingly. 

Taking a deep breath, Byleth slowly let it out, the soft scent of lilies and crisp snow filling her senses. It did not take her long to once again succumb to slumber, safe and warm in Rhea’s embrace.

**-++-**

The first thing Rhea noticed when she awoke was, coincidentally, also the warmth.

For centuries she’d been alone, had made sure to keep a certain careful distance from even her fellow Nabateans. Having had her world suddenly torn apart once, and so violently at that, had made her very careful to shield her heart from fully opening itself to another once more. The risk of pain had been too great, and so instead she had thrown herself into the only course she could see that promised even a glimmer of a happy future. 

To that effect, she had made it her life’s goal to bring her mother back to the mortal plane so that she might once again be held in her arms - so that she might once again love and be loved without fear or reservation.

It was perhaps ironic, then, that the very reason she ultimately failed in her goal of resurrecting her mother, was also the one who had unwittingly snuck their way into the parts of her heart she had kept so carefully locked away.

Rhea kept her eyes closed, and simply took a moment to _feel_.

She felt the slight weight of the body pressed softly against her own.

She felt the gentle rise and fall of Byleth’s chest - felt the soft exhales tickle across her skin.

She felt the warmth that could only come from another living being encompass her, chasing away the cold she’d lived with for so long.

She felt a sense of deep and utter confusion as to how the dear child – no, the dear _woman_ – laying within her arms could sleep so peacefully after all that she had done.

Without even counting the many actions she’d taken in the past that had caused the young woman’s fate to be so cruel, Rhea could also vividly remember her most recent transgression.

She had not been in control of herself – no, her mind had been twisted by rage and madness as her Crest Stone destabilized, flooding her with uncontrollable power. But she _had_ been just aware enough that the memories now played across her mind with a sickening clarity.

Not only had she tried to kill the young woman in her arms.

She had, to her horror, almost _succeeded_.

Swallowing thickly, her arms reflexively tightened around Byleth’s waist as she attempted to push those memories to the side, at least for the moment. Byleth, still asleep, reacted to her actions by nuzzling deeper into her embrace, a slight murmur escaping softly parted lips as they brushed against her skin.

Rhea relaxed, the tension melting off her frame. A sweet smile tugged at her lips as she sighed and finally opened her eyes, her gaze focusing on what she could of the mess of pale green splayed across her chest with an infinite fondness. In that moment she wished she could brush a kiss against the pale skin just a few shades darker than her own, but she daren’t move in such a way, not wanting to risk waking her slumbering companion.

Instead she began moving her thumb in slow soothing circles where it lay against Byleth’s waist, the digit smoothing at the hint of soft skin between shirt and shorts.

“She gave you her blood.” 

Rhea’s gaze flicked upwards and landed on the man standing just inside her open door. Lost in thought as she’d been, she had not heard him enter.

“Seteth,” Rhea spoke softly in acknowledgment, not wanting to wake her companion. Guilt gnawed at her once more as visions of viciously lashing out and striking the other Nabatean flickered through her mind – only for her to freeze as his words finally registered. 

Rhea’s eyes widened. “What? She-,”

“You were out of immediate danger, due in no small part to Sothis’ intervention,” Seteth continued as he leaned against the wall, arms crossed. His gaze shifted to stare at the slumbering young woman, his position only allowing him to glimpse a hint of pale green hair poking out from the blankets. “Your Crest Stone had stabilized enough that you were in the early stages of healing sleep. With time, you would have awoken, perfectly healthy.”

He tilted his head in Byleth’s direction. “She would not accept that – would not accept that the two of you would have to be parted by time even if only for a little while – and so took her dagger and opened a vein right there in the cathedral. She nearly collapsed herself after ignoring my words of caution, intent as she was to give you as much of her blood as it took.”

Rhea could not help the look of mixed concern and disbelief that appeared on her face as she gazed once more at the young woman who held her heart. Eventually, her expression melted into undisguised awe.

Seteth gave the shocked woman a moment to process his words, his scrutinizing gaze shifting from Byleth to the speechless Rhea. Finding what he was looking for after a long moment, he nodded to himself in satisfaction before pushing off from the wall. “Those are not the type of actions one takes for someone they view as a monster.”

Rhea looked back over at Seteth. Slowly she nodded, her voice soft and heartfelt, “…Thank you.”

Seteth tilted his head slightly, a small smile sliding across his face before he bowed out of the room, the door shutting silently behind him.

Rhea couldn’t help herself, and carefully disentangled one of her arms only to brush a gentle hand softly through silken green. Byleth shifted slightly at her ministrations, a soft sigh escaping her as Rhea continued to stroke her hair softly. 

“Perhaps,” Rhea murmured. In that moment, she decided to take a chance – to try, one last time, to seek what her heart desired most. 

In that moment, as she looked down at Byleth, her unguarded gaze was raw and full of hope.

Perhaps, after countless years of existing in the cold, she would not have to give up the warmth that she had finally found after so long.

**-++-**

**Notes for the Chapter:**

> Make sure to check out the link for **Thank You** by **unquenchable_flame** because it is amazing. 
> 
> Thank _You_ for the awesome art accompaniment.

**Works inspired by this one:**

  * [Thank you](https://archiveofourown.org/works/23747299) by [unquenchable_flame](https://archiveofourown.org/users/unquenchable_flame/pseuds/unquenchable_flame)




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